X-Git-Url: https://mattmccutchen.net/match/match.git/blobdiff_plain/00f7bf547ecc8b9a709c6fbeff55b9b0d05ecffe..fd0d2377785ca843a46b0050a7351dac82c84777:/program/NaiveMinCostFlow.hs

diff --git a/program/NaiveMinCostFlow.hs b/program/NaiveMinCostFlow.hs
index 1347837..94ee20d 100644
--- a/program/NaiveMinCostFlow.hs
+++ b/program/NaiveMinCostFlow.hs
@@ -1,4 +1,5 @@
 module NaiveMinCostFlow (minCostFlow) where
+import IMinCostFlow
 import BellmanFord
 import MonadStuff
 import Data.Array.IArray
@@ -75,14 +76,8 @@ doFlow state = do
 			augment state augAmt augPath
 			doFlow state
 
-minCostFlow :: forall s gr a b i f c. (Graph gr, Ix i, Real f, Real c) =>
-	(i, i)       -> -- Range of edge indices
-	(b -> i)     -> -- Edge label -> unique edge index
-	(b -> f)     -> -- Edge label -> flow capacity
-	(b -> c)     -> -- Edge label -> cost per unit of flow
-	gr a b       -> -- Graph
-	(Node, Node) -> -- (source, sink)
-	Array i f       -- ! edge index -> flow value
+-- We need to put the type parameters in scope for the mkGraph call.
+minCostFlow :: forall gr a b i f c. (Graph gr, Ix i, Real f, Real c) => MinCostFlowImpl1 gr a b i f c
 minCostFlow idxBounds edgeIdx edgeCap edgeCost theGraph (source, sink) = runSTArray (do
 		let ourFlipF isRev l =
 			MCFEdge (edgeIdx l) (edgeCap l)
@@ -93,7 +88,12 @@ minCostFlow idxBounds edgeIdx edgeCap edgeCost theGraph (source, sink) = runSTAr
 				(n1, n2, MCFEdge (edgeIdx l) (edgeCap l) (  edgeCost l ) False),
 				(n2, n1, MCFEdge (edgeIdx l)  undefined  (-(edgeCost l)) True )
 			]) $ labEdges theGraph) :: gr a (MCFEdge i f c)
-		flow <- newArray idxBounds 0
+		-- Initialize only the slots of the flow array corresponding to
+		-- existing edges to zero to catch buggy callers that query
+		-- nonexistent edges.
+		flow <- newArray idxBounds undefined
+		sequence $ map (\(_, _, l) -> writeArray flow (edgeIdx l) 0)
+			(labEdges theGraph)
 		let state = MCFState graph2 source sink flow
 		doFlow state
 		return (mcfFlow state)